Chapter 4 - Development Flashcards
gametes
sperm and secondary oocytes; produced by gonads (testes and ovaries)
sexual reproduction
process by which organisms produce offspring
developmental biology
study of the sequence of events from the fertilization of a secondary oocyte by a sperm cell to the formation of an adult organism
embryonic period
fertilization to 8th week of development
embryo
developing human
embryology
study of development from fertilization to the 8th week
fetal period
week 9 until birth
fetus
developing human from week 9 until birth
prenatal development
time from fertilization to birth and includes both embryonic period and fetal period. divided into 3 periods, trimesters
first trimester
most critical stage of development; all major organ-systems begin to develop; embryo most vulnerable to the effects of drugs, radiation, and microbes.
second trimester
characterized by the nearly complete development of organ-systems; at end of stage fetus assumes distinctly human features
third trimester
rapid fetal growth in which the weight of the fetus doubles; during early stages most organ systems become fully functional
ovaries
paired organs in the superior portion of the pelvic cavity on either side of the uterus;produce secondary oocytes and discharge them into the peritoneal cavity each month (ovulation)
Fallopian tubes
extend laterally from uterus, path for embryo from peritoneal cavity
uterus
inverted pear-shaped organ in the pelvic and lower abdominal cavity; consists of a superior portion (fundus), middle portion (body), and inferior portion (cervix)
uterine cavity
interior body of uterus
cervical canal
interior of cervix
endometrium
vascular, glandular lining of uterus at menstration
myometrium
largest mass of smooth muscle in body; underneath endometrium; responsible for strong contractions to expel endometrium.
vagina
multi-purpose canal attached to cervix and open to the exterior
fertilization
genetic material from aa haploid sperm cell and a haploid secondary oocyte merges into a single diploid nucleus
capacitation
series of functional changes that cause the sperms tail to beat even more vigorously and prepare its plasma membrane to fuse with the oocytes plasma membrane.
corona radiata
cells that surround the secondary oocyte
zona pellucida
clear glycoprotein layer between the corona radiata and the oocytes plasma membrane
acrosome
helmetlike structure that covers the head of the sperm, contains several enzymes
acrosomal reaction
release of contents of the acrosome
syngamy
fusion with the oocyte
polyspermy
fertilization by more than one sperm cell
path of sperm cell
corona radiata -> zona pellucida ->plasma membrane of secondary oocyte -> cytoplasm of secondary oocyte
dizygotic (fraternal) twins
produced from the independent release of 2 secondary zygotes and the subsequent fertilization of them by 2 sperm
monozygotic (identical) twins
develop from a single fertilized ovum; contain exact same genetic code; separation of zygote into 2 embryos, 99% of the time within 8 days of fertilization
conjoined twins
often result of zygote separation after first 8 days of fertilization.; share some body structures
ectopic pregnancy
occurs outside uterus, often in Fallopian tubes
cleavage
zygote undergoes miotic cell division that initially increase the number of cells without increasing the overall size of the cell mass; first division begins ~24 hours after fertilization and ends 6 hours later
blastomeres
progressively smaller cells produced by clevage
morula
solid sphere of cells from clevage
uterine milk
glycogen-rich secretion from the glands of the endometrium, passes into the uterine cavity and enters the morula through the zona pellucida
blastocyst cavity
large fluid cavity collecting blastomeres
blastocyst
day 5 after fertilization; hundreds of cells but same size as original zygote
embryoblast
inner cell mass; located internally and eventually develops into the embryo and some of the extraembryonic membranes
trophoblast
outer superficial layer of cells that forms the sphere like wal of the blastocyst
placenta
site of exchange of nutrients and waste between mother and fetus
implantation
6 days after fertilization the blastocyte loosely attaches to endometrium
decidua
functional layer of the endometrium
decidua basalis
portion of the endometrium beneath the implanting embryo; later becomes maternal part of the placenta
decidula parietalis
the remaining modified endometrium that lines the noninvolved areas of the rest of the uterus
decidua capsularis
the portion of the endometrium that will cover the embryo after it implants in the endometrium
stem cells
unspecialized cells that have the ability to divide for undefined periods and give rise to specialized cells
therapeutic cloning
envisioned as a procedure in which the genetic material of a patient with a particular disease is used to create pluripotent stem cells to treat the disease
syncytiotrophoblast
2 layers in the region of contact b/w the blastocyst and endometrium; no distinct boundary
cytotrophoblast
area b/w the embryoblast and syncytiotrophoblast that has distinct cell boundaries
key hormone in maintenance of pregnancy
hCG
